There is a desire to disperse, diffuse and/or dissolve substances in liquids and this may be particularly desirable with liquids contained in bottles. Although dissolvable items may be dropped into a bottle containing liquid, for example, a bottle of water, in some circumstances, the substance can degrade over time. Therefore, there is a desire to dissolve the substance just before use or consumption. Additionally, some substances are used to impart a flavour to a liquid rather than dissolving itself in the liquid. However, where the substance does not dissolve, it is desirable to prevent it being poured back out of the opening to the bottle, particularly, where a substance imparts a flavour and it is not desirable to consume the substance. Thus, there is a need to allow it to mix with the liquid but for the substance to remain in the bottle so that it is not consumed.